Disinfecting solutions for use with contact lenses are well known in the art and the use of such lenses involves a daily disinfecting treatment. Flexible, or soft, contact lenses are generally made from hydrophilic polymers and the hydroxy groups of these lenses attract and retain substantial amounts of water in the plastic which results in difficulties during cleaning and sterilization.
Furthermore, hydrophilic flexible contact lenses have a tendency to complex with and concentrate certain preservatives and disinfecting agents used in sterilizing conventional contact lenses. If these preservatives come into contact with the cornea they can cause severe irritation and burning.
Hydrogen peroxide systems, and particular a 3% hydrogen peroxide solution, have emerged as the disinfectant of choice for all types of daily and extended wear hydrogen lenses. The primary reason for its increasing popularity is its rapid kill of microbial contaminants and its non-residual character. After hydrogen peroxide disinfects lenses, it can be converted into innocuous by-products which are compatible with ocular physiology. See Krezanoski et al., "Journal of the American Optometric Association", Vol. 59, Number 3, pages 193-197 (1988).
A great deal of patent literature is available concerning hydrogen peroxide contact lens disinfection systems. Reference is made in this respect to the following:
Gaglia, Jr., U.S. Pat. No. 3,912,451 PA1 LeRouzic et al., U.S. Pat. No. 4,743,447 PA1 Andermann et al., U.S. Pat. No. 4,880,601 PA1 Giefer, U.S. Pat. No. 4,585,488
Davies et al., International Pat. Publication WO 86/05695
In general, the hydrogen peroxide systems involve a hydrogen peroxide-containing disinfecting solution into which the contact lenses to be disinfected are placed and allowed to remain for a required period of time. Nascent oxygen is released providing a germicidal effect. Following the requisite time period a purposeful inactivation of the hydrogen peroxide is conducted, for example, with a platinum catalyst. Following inactivation, the contact lens may be reinserted into the eye.
The hydrogen peroxide disinfecting solutions may be of the buffered or unbuffered type. As examples, AOSept R is a stabilized 3% hydrogen peroxide solution made isotonic with sodium chloride and buffered to an approximate pH 6.9 with phosphates. On the other hand, LenSept R is a non-buffered 3% hydrogen peroxide formulation.